Usual recruiter call, followed by a tech screen. From my experience (two times) so far, the interviewers are junior engineers and looking to hire more college grads rather than experienced persons. It's not that I wasn't able to complete the coding challenge, but every time they found some excuse to pass me on, even though I was able to complete the problem in time. The questions are pretty simple and very basic.

For anyone interviewing at Facebook without a referral, I would recommend avoiding the onsite for the first round and taking it on the phone instead.

Implement binary search.

Find the maximum length of continuous subarrays within an array (DP).